When I record bass I always plug in to the laptop via an external audio card or similar device. I use AudioKontrol if I want to add effects or modeling later (in Cubase or GarageBand) or a Korg Pandora 4 if I want to use its effects and patches.

To mic the amp can be very, very complicated and perhaps you will get a better sound if you plug in the bass directly.

It's common practice to both mic an amp as well as use a DI. As far as mic placement, use your ears. You'll get more treble toward the center of the cone. An sm 57 slightly off axis is always a good bet.